Method for producing functional polyimide fine particle and rewritable memory material utilizing change in fluorescence characteristics caused in fluorescence characteristics caused by light irradiation or heat treatment

ABSTRACT

A rewritable photomemory material obtained by combining a polymer possessing a carbonyl group in a main chain or a side chain with a function-imparting component such as a compound which produces rare earth ions is disclosed. The magnitude of fluorescence level of the rewritable phtomemory material can be intensified by light irradiation, while an initial state can be recovered by a heat treatment. Fine particle materials imparted with functions such as fluorescence characteristics, magnetic characteristics, coloration or non-linear characteristics are also disclosed, and particularly a fine particle material imparted with heat resistance through combination with polyimide is disclosed.

FIELD OF THE INVENTION

The, present invention relates to a functional film prepared from asolution comprising a functional component and a polymer constituent, afunctional particle with not less than 5 nm and not more than 10000 nmin diameter which comprises a polymer constitute containing a functionalcomponent prepared by re-precipitation method from the solution and amethod for preparation of said particles from a solution containing thepolymer and the functional component by re-precipitating said functionalparticle by the prepared solution being poured into a solvent which ispoor solvent to said polymer and functional component. More in detail,the present invention relates to a photomemory material comprising apolymer with a carbonyl group to which an ion of element belonging torare-earth elements, especially lanthanides, is contained as a functionproviding component, a polymer film containing an ion of rare-earthelements possessing a photomemory characteristic produced by using anion of said rare-earth elements and a solution of said polymer, or apolymer film containing an ion of said rare-earth elements formed frompolymer fine particles containing an ion of rare-earth elementspossessing a photomemory characteristic produced by reprecipitation andwith particle size in diameter from 5 nm to 10000 nm or from a solutioncontaining said polymer fine particles. Since said polymer film, fineparticles or fine particle film are characterized that magnitude offluorescence level intensifies along with the increase of photoirradiation energy, in other words, along with the increase of theproduct of irradiation intensity×irradiation time, while the magnitudeof fluorescence level decreases to the initial state along with theelevation of temperature of heat treatment, said polymer film, fineparticles or fine particle film can be used as a rewritable photomemorymaterial which utilizes said change of fluorescence. Further, thepresent invention relates to a method to produce a polyimide fineparticle possessing said rare-earth ion, transition metal ion orpigment, in particular, an polyimide particle with particle size indiameter from 5 nm to 10000 nm by forming polyamide acid fine particlespouring a solution of polyamide acid containing a compound which forms arare-earth ion or a transition metal ion or a solution of polyamide acidin which a pigment is dissolved in a poor solvent so as a polyamide acidfine particles possessing said rare-earth ion, transition metal ion orpigment to be formed by a reprecipitation method, then imidizing saidpolyimide fine particles possessing said rare-earth ion, transitionmetal ion or pigment.

BACKGROUND OF THE ART

Along with the recent progress of informationalized society, a recordingmaterial which makes high density and high speed treatment possible isbeing required, and attempting the improvement of recording density bydeveloping a recording medium which is possible to shorten thewavelength of light wavelength and makes narrow the width of a pit bysaid shortening of the wavelength. However, at the accomplishment of ahigh density recording medium, a multiple recording material which makesseveral bits recording par one pit possible is desired in stead ofconventional one bit par one pit recording. Further, from the view pointof requirement for the art gentle to environment, a material which has acharacteristic of rewritable is required besides said recordingcharacteristic. In Document 1, Shinya MAENOSONO, Ceco Danov DUSHKIN,Soichiro SAITA and Yukio YAMAGUCHI, “Optical Memory Media Based onExcitation-Time Dependent Luminescene from a Thin Film of SemiconductorNanocrystal” Japanese Journal of Applied Physics 39, 4006-4012 (2000),there is following recitation reciting that a fine particle of CdSewhose surface is capped by tri-octylphosphine oxide prepared by adding asolution of dimethylcadmium, selenium-tri-butylphosphine totri-octylphosphine oxide, maintaining the obtained solution at thetemperature of 300° C. under argon atmosphere by constant stirringindicates 7 times stronger intensity to the initial magnitude offluorescence level along with increase of irradiation time of laserlight of 430 nm wavelength and 15 mW and saturated by 500 minutes andthe intensity of intensified luminescence is stable more than 500 hours.However, there is no recitation reciting erasion of fluorescence. InDocument 2, Masayuki Nogami, “Room temperature persistent spectral holeburning of Eu³⁺ ions doped in sol-gel derived glasses” Journal ofLuminescence 98, 289-294 (2002), the author proposes that a hole isformed by irradiating Rhodamine 6G laser of spot size 1 mm toalminosilicate glass containing Eu³⁺ prepared by a sol-gel method at−196° C. (77 k) by 300 W, further, there is a passage stating that ahole is formed in a same way by irradiating X-ray at room temperatureand depth of the hole can be reduced by elevating the temperature, andproposes that several bits record can be obtained by changing depth of ahole. In Document 3, Nobuhiko Umezu, Tsunenori Asatsuma, YoshihiroTakemoto, Masahiro Kaneko “Multi-wavelength recording at roomtemperature by gated persistent spectral hole burning inSrFCl_(0.5)Br_(0.5):Sm²⁺” Journal of Luminescene 64, 195-199 (1995),there is a record reporting that multi-wavelength recording is possibleby forming many holes in an excitating spectrum of Sm²⁺ by irradiatingpigment laser of multi-wavelength within the range from 688 nm to 693 nmto a powder of SrFCl_(0.5)Br_(0.5) containing a Sm²⁺ ion and make highdensity record possible. However, since the depth of hole reported inthese documents are shallow and broad, a threshold value becomes vague.

Accordingly, these recording materials can not be said as a sufficientrecording material which satisfies room temperature recordingcharacteristic and high resolution characteristic which are required toa recording material in the informationalized society. Further, from theview point of productivity of a recording material, these recordingmaterials can not be said as a sufficient one. In the meanwhile, a fineparticle, in the present invention, a particle with particle size indiameter approximately from 50 nm-10000 nm is called as a fine particle,a fine particle of said form can be easily changed or processed tovarious shapes by joining the particles from one dimensional shape tothree dimensional shape and is very easy for handling as a material,further, there are many production techniques of inorganic fine particlepossessing a functionality. On the contrary, although polymer has anadvantage that can be processed to a fine particle by mild condition bylower cost and is light weight, many polymers have problems of lowerheat resistance, lower light resistance, lower chemical agent resistanceand have a defect of inferior mechanical intensity. On the contrary,polyimide is an excellent polymer which does not have such defects andan investigation for making fine particle of polyimide is carried out,however, a technique to make a fine particle posses a functionality isnot developed yet, accordingly, there is no idea to blend an componentwhich provides the functionality to a solution for forming a polyimidefine particles. In Document 4, Jun Hu et al. Journal of Applied PolymerScience, 89, 1124-1131 (2003), an invention of a method for preparationof submicron PMMA particle containing rare earth ion by polymerizingrare earth ions and a monomer which forms said polymer under irradiationof microwave in the condition of not existing an emulsifier is recorded.Further, in Document 5, Katsuya Asao et al, Kobunshi ronbunshu, vol 57,No. 5, pp. 271-276, May 2000, in particular in items 2 and 3,preparation of polyimide fine particles, a method for preparation ofpolyimide fine particle comprising, producing polyamide acid, which is aprecursor of polyimide, by reacting tetracarboxilic acid dianhydride anddiamine in an aprotic polar solvent and obtaining polyimide fineparticles as precipitation by adding toluene in said polyamide acidsolution and refluxing so as to progress heat imidization reaction isdisclosed. Still further, in Document 6, Abstract of Polymer Scienceannual forum, Vol. 50, No. 3 (2001), pp 484, III F08, Title “Preparationof polyimide fine particles by a reprecipitation method”, a method forpreparation of polyimide fine particle using polyamide acid solution,which is a precursor of polyimide obtained by reacting tetra carboxylicacid dianhydride and diamine in an aprotic polar solvent, then producingpolyimide fine particles by thermally or chemically imidizing aboveobtained fine particles of polyamide acid is disclosed. Furthermore, inDocument 8, Japan Patent Publication 2003-84332 (published on Mar. 19,2003), an invention of “A method for preparation of inorganic fineparticle-organic crystal hybrid fine particle comprising; pouring anorganic material having π-conjugated bond as a water soluble solutioninto aqueous dispersion in which inorganic fine particles of 50 nm orless selected from the compound group consisting of metal fineparticles, semi-conductor fine particles, fine particles of inorganicfluorescent material and fine particle of inorganic luminescentmaterial, are dispersed, co-precipitating said inorganic fine particlewhich forms a core into said organic material which forms a shell insaid dispersion and forming shell of fine crystal of said organicmaterial on the surface of the core of said inorganic fine particles of50 nm or less by controlling the size of said inorganic fine particleand by controlling the adding amount of said organic material.” isdisclosed and a method for preparation of hybrid nano particlesconsisting of inorganic fluorescence material fine particles orinorganic emission material fine particles and organic fine particles bya reprecipitation method using inorganic fluorescence material fineparticles or inorganic emission material fine particles, specificallyZnS (refer to of the publication) or organic material, organic materialwhich is possible of solid-state polymerization, specifically usingdiacetylene is disclosed. The author of the document refers thegeneration of interaction at the surface of both compounds by saidhybrid fine particle.

However, document which refer to obtain fine particles prepared bymaking contain rare earth ions and pigment to polyimide resin, which isexcellent in heat resistance, especially fine particles with particlesize in diameter from 5 nm to 10000 nm is not found.

The first subject of the present invention is to provide a photomemorymaterial which is characterized that the recorded memory is stable inroom temperature, multiple recording of multiple bits for 1 pit ispossible and rewriting of record is possible utilizing a change offluorescence characteristic by light irradiation. The inventors of thepresent invention have found that an ion of elements of rare earth,especially, belonging to lanthanide, which is contained in polymerpossessing carbonyl group, for example, imide group, carboxyl group orester group thereof can enhance magnitude of fluorescence level of rareearth ion depending on photo irradiation amount, that is, irradiationintensity×irradiation time, especially, in a case of polyimide canenhance magnitude of fluorescence level 400 times in maximum, andluminescence intensity characteristic after light irradiation is stoppedis stable for several months at room temperature, and have found thathigh density record can possible by providing various thresholds ofirradiation amount. Further, the inventors of the present invention haveaccomplished the elimination of magnitude of fluorescence level byputting back to initial state by heat treatment, utilizing flexiblestructure of polymer. Furthermore, the inventors of the presentinvention have found that after elimination of fluorescence, magnitudeof fluorescence level can be intensified again by irradiation of lightdepending on light irradiation amount. Since above mentioned photomemoryis possible not only by a film but also by a shape of fine particle of 5nm size, the inventors of the present invention have found that highresolution record is possible and have accomplished the 1^(st) subjectof the present invention.

The second subject of the present invention is to provide fine particlesof polyimide possessing fluorescence, non-linear and luminescencecharacteristics using polyimide resin which is superior in heatresistance, especially, to provide fine particles of 5 nm-10000 nmparticle size indiameter. For the accomplishment of said 2^(nd) subjectof the present invention, the inventors of the present invention have aconception as follows. As the first step, by containing a compound or adye forming rare earth ion or transition metal ion which provides saidfunctionality to polyimide resin at a production process of fineparticles, a functionality providing material can be existed in a statethat said functionality is provided stable in fine particles or in astate to generate a new function by hybrid with polyimide, producing amaterial for hybrid fine particle composed of polyamide acid and a rareearth ion or a transition metal ion by re-precipitation method from asolution of a compound or a dye which forms said rare earth ion ortransition metal ion with polyamide acid which is a precursor ofpolyimide resin. Then, a material for hybrid fine particle composed of arare earth ion, a transition metal ion or a dye and a polyimide resin isobtained by crosslinking the polyimide resin by well-known crosslinkingmeans in the technical field of the art, for example, heating orchemical crosslinking method. Fluorescence characteristic etc ofpolyimide resin containing rare earth ion are investigated, and theusefulness of the material for hybrid fine particle composed ofpolyamide acid and a rare earth ion can be confirmed. Further, it isunderstood that fine particles possessing coloring characteristic andnon-linear characteristic of said dye can be obtained from a dye andpolyimide resin, and in hybrid fine particles composed of polyimideresin and a transition metal resin, fine particles havingcharacteristics based on the characteristic of transition metal that theparticle size is uniform, for example, in a case of nano size fineparticles indicates a characteristic which generates a quantum effectcan be provided. As mentioned above, the second subject of the presentinvention is accomplished.

DISCLOSURE OF THE INVENTION

The first invention relating to the first subject is,

-   (1) a photomemory material comprising a polymer with a carbonyl    group in a main or a side chain of the polymer containing rare earth    element ion characterized in which magnitude of fluorescence level    is intensified corresponding with applied photo irradiation    intensity and is able to restore to initial state by applying heat    treatment.    In detail, desirably,-   (2) the photomemory material as described in said (1), wherein the    polymer possessing a carbonyl group is a polyimide obtained by a    reaction of tetracarboxylic acid or di-anhydride thereof with    diamine, or, (3) the photomemory material as described in said (1),    wherein the polymer possessing a carbonyl group is a polymer    possessing a carboxylic group or an ester group thereof in a said    side chain, further desirably, (4) the photomemory material as    described in said (3), wherein the polymer possessing a carboxylic    group or an ester group thereof in a said side chain is a polymer    obtained by an addition polymerization of ethylene unsaturated    group, furthermore desirably, (5) the photomemory material as    described in said (1), (2), (3) or (4), wherein the rare earth    element is selected from the group consisting of elements whose    atomic number is 58 or more and 70 or less.

The second invention relating to the first subject is,

-   (6) relates to a photomemory material is polymer fine particles    containing a rare earth element ion with particle size indiameter    from 5 nm to 10000 nm obtained by a method which comprise of a step    obtaining a solution containing said polymer and said rare earth    element ion by dissolving a polymer possessing a carbonyl group in a    main or a side chain of the polymer and a compound of the rare earth    element which forms the rare earth element ion into a solvent which    dissolves said two components, and a step pouring said solution    dissolving said two components into a poor solvent which poorly    dissolves said two components and re-precipitating said two    components to obtain said polymer fine particles, and related to a    polymer film or a bulky molded product obtained by a method which    comprise of a step obtaining the solution containing said polymer    and said rare earth element ion by dissolving a polymer possessing a    carbonyl group in a main or a side chain of the polymer and a    compound of the rare earth element which forms the rare earth    element ion into the solvent which dissolves at least said two    components, the step pouring said solution dissolving two components    into a poor solvent which poorly dissolves said two components and    re-precipitateing said two components to obtain the solution    containing polymer fine particles containing said rare earth element    ion with the property of photomemory and particle size in diameter    from 5 nm to 10000 nm, and the step forming the said polymer film or    the bulky molded product composed of said polymer fine particles    containing said rare earth element ion.

The first invention of said second subject is,

-   (2-1) a method for production of polyimide fine particles whose    particle size is from 5 nm to 10000 nm containing a rare earth ion    or a transition metal ion or a pigment comprising, pouring polyamide    acid solution prepared by dissolving a compound which forms a rare    earth ion or a transition metal ion or a pigment compound in a    solution which forms said ions to a poor solvent to said rare earth    ion or transition metal ion or the pigment compound and the    polyamide acid, forming fine particles of polyamide acid containing    the rare earth ion or the transition metal ion or the pigment, then    carrying out imidizing treatment on the formed fine particles of    polyamide acid.    Desirably, the first invention of said second subject is,-   (2-2) the method for production of polyimide fine particles whose    particle size is from 5 nm to 10000 nm containing a rare earth ion    or a transition metal ion or a pigment of (2-1) comprising, using    polyamide acid solution dissolving a compound which forms 0.1-10    weight % of rare earth ion or transition metal ion or a pigment    compound, more desirably, (2-3) the method for production of    polyimide fine particles whose particle size is from 5 nm to 10000    nm containing a rare earth ion or a transition metal ion or a    pigment of (2-1) or (2-2) comprising, using acetone, acetonitrile,    tetrahydrofuran or chloroform as a solvent to prepare polyamide acid    solution, furthermore desirably, (2-4) the method for production of    polyimide fine particles whose particle size is from 5 nm to 10000    nm containing a rare earth ion or a transition metal ion or a    pigment of (2-1), (2-2) or (2-3), wherein the poor solvent is    decalin, cyclohexane, hexane, benzene, toluene, water, alcohols, CS₂    or mixture of two kinds or more, still further desirably, (2-5) the    method for production of polyimide fine particles whose particle    size is from 5 nm to 10000 nm containing a rare earth ion or a    transition metal ion or a pigment of (2-1), (2-2), (2-3) or (2-4)    wherein the temperature of the poor solvent is adjusted from −20° C.    to 60° C., yet further desirably, (2-6) the method for production of    polyimide fine particles whose particle size is from 5 nm to 10000    nm containing a rare earth ion or a transition metal ion or a    pigment of (2-1), (2-2), (2-3), (2-4) or (2-5) wherein the rare    earth element ion is an element selected from the group consisting    of the element whose atomic number is 58 or more and 70 or less.

BRIEF ILLUSTRATION OF THE DRAWING

FIG. 1 shows the correlation between irradiation time and magnitude offluorescence level belongs to Eu³⁺, when light of 6 W and wavelength 254nm is irradiated to a polyimide film containing Eu³⁺ obtained in Example1 using an UV lamp.

FIG. 2 shows the correlation between heat treatment temperature of apolyimide film containing Eu³⁺ obtained in Example 1 when magnitude offluorescence level is saturated by said UV irradiation and reduction ofmagnitude of fluorescence level. Fluorescence is eliminated perfectly at200° C.

FIG. 3 shows the correlation between irradiation time when UV light isfurther irradiated after fluorescence is eliminated by the heattreatment at 200° C. shown in FIG. 2 and magnitude of fluorescence levelbelonging to Eu³⁺. That is, this fact indicates the possibility of usageas a rewritable recording material.

FIG. 4 shows the correlation between irradiation time when light of 6 Wand wavelength 254 nm is irradiated to a polyimide film containing Tb³⁺obtained in Example 2 using an UV lamp and magnitude of fluorescencelevel belonging to Eu³⁺.

FIG. 5 shows that the magnitude of fluorescence level is saturated by 3hours when light of 6 W and wavelength 254 nm is irradiated to apolyamide acid film containing Eu³⁺ obtained in Example 4 using an UVlamp.

FIG. 6 shows the fact that the light of 6 W and wavelength 254 nm isirradiated to a polyacrylic acid film containing Eu³⁺ obtained inExample 5 using an UV lamp and along with the increase of irradiationtime, magnitude of fluorescence level belonging to Eu³⁺ is intensified,and the magnitude of fluorescence level is saturated by 24 hours.

FIG. 7 shows the SEM picture of polyacrylic acid fine particlescontaining Eu³⁺ obtained in Example 7.

FIG. 8 shows the process illustration of a producing process ofpolyimide fine particles containing a rare earth element ion, afluorescence compound or an organic pigment by re-precipitation methodrelating the first invention of said second subject, and in A, Bprocesses prescribed amount of polyamide acid solution 3 containingfunctionality providing component is poured into a poor solvent 1, andpolyamide acid fine particles containing prescribed amount of saidfunctionality providing subject is obtained by re-precipitation method.When solvent 3 is poured, said poor solvent is stirred by a stirrer 2.

FIG. 9 shows the SEM picture of polyimide fine particles containing Eu³⁺obtained in Example 8.

FIG. 10 shows the fluorescence spectrum when polyimide fine particlescontaining Eu³⁺ obtained in Example 8 is irradiated by exited light ofwavelength 280 nm.

FIG. 11 shows the fluorescence spectrum when polyimide fine particlescontaining Tb³⁺ (a) and Ce³⁺ (b) obtained in Example 9 is irradiated byexited light of wavelength 280 nm.

FIG. 12 shows the SEM picture of polyimide fine particles containingEu³⁺ obtained in Example 10 produced by using polyamide acid-Eu(NO₃)₃wherein blending amount of Eu³⁺ is 1 wt % (a), 5 wt % (b) and 10 wt % topolyamide acid.

FIG. 13 shows the fluorescence spectrum when polyimide fine particlescontaining Eu³⁺ obtained in Example 10 produced by using polyamideacid-Eu(NO₃)₃ wherein blending amount of Eu³⁺ is 1 wt % (a), 5 wt % (b)and 10 wt % to polyamide acid is irradiated by exited light ofwavelength 280 nm.

FIG. 14 shows the SEM picture of polyimide fine particles containingquinacridone obtained in Example 11.

FIG. 15 shows the SEM picture of polyimide fine particles containingEu³⁺ obtained by adjusting the temperature of cyclohexane, which is apoor solvent to 10° C. (a), 25° C. (b) and 40° C. (c) in Example 13.

FIG. 16 shows the SEM picture of polyimide fine particles containingFe((NO₃)₃ (a) or FeCl₃ (b) or CuSO₄ (c) as a compound containingtransition metal obtained in Example 15.

The present invention will be illustrated more in detail.

In the invention relating aforementioned 1^(st) subject,

A. It is important that the material composing a rare earth ion to existin a polymer material possessing a carbonyl group, to form differentcoordination states by light irradiation and to maintain the statestable at room temperature. As a rare earth element to form saidcoordination state, an element belonging to lanthanide, desirably, anelement whose atomic number is from 58 to 70, more desirably, an elementselected from the group consisting of Eu, Tb, Gd and Ce. These elementshave a specific fluorescence peak wavelength and records correspondingto multiple transitions characterizing that the intensify of magnitudeof fluorescence level are different.

B. It is important that the polymer material to maintain an rare earthelement ion of said coordination state stable at room temperature, andsince it is conjectured that the coordinate bond state of a rare earthelement ion and oxygen, namely, “rare earth element ion—O” is desirableto maintain said multiple coordinate bond state, a polymer whichpossesses a carbonyl group in a main or a side chain of the polymer isused as a desirable polymer.

From the electronic theory relating to the coordinate bond state, it isimportant that energy gap of HOMO and LUMO of polymer, ground state ofrare earth element ion and energy gap of exiting state are correspondingto said condition, for realization of energy transportation between thepolymer and the rare earth element ion.

B-1. As a desirable polymer, polyimide can be mentioned first. Astetracarboxylic acid or dianhydride thereof, 3,3′-4,4′-benzophenontetracarboxylic acid (BTDA), 3,3′-4,4′-tetracarboxybiphenyl,2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane and dianhydridethereof can be mentioned.

B-2. As a diamine to form polyamide acid, which is a precursor ofpolyimide, by reacting with said tetracarboxylic acid or dianhydridethereof and forms polyimide by followed imidization,4,4′-diaminodiphenylether, 4,4′-bis(4-aminophenoxy)biphenyl,1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene,1,4-diaminobenzene, 4,4′methylenebis(methylcyclohexylamine),4,4′methylenebis(ethylcyclohexylamine) can be mentioned.

B-3. As another polymer, an addition polymerized polymer of monomerwhich possesses ethylene unsaturated bond such as polyacrylic acid orpolymethylmethacrylate (PMMA) having a carboxylic group or an estergroup in a side chain.

C. Particle size is important from the view point of effective use ofrecording light. It is possible to obtain a particle of 5 nm particlesize in which said rare earth element ions are uniformly dispersed, bypreparing a solution in which said rare earth element is existing as anion by dissolving said polymer and rare earth element compound, pouringsaid solution into a poor solvent of these two components and producefine particles, that is, by means of a reprecipitation method.

D. Method for production of a recording material

As a method for production of above mentioned photomemory material,following production steps are used. Namely, 1-10 weight % of rare earthsalt is blended to a polymer possessing a carbonyl group in a main or aside chain of the polymer, said polymer is dissolved in a solvent,desirably in a polar solvent for the purpose to exist said rare earthsalt as an ion in the solution, by 0.1-15 weight % concentration,obtained polymer solution is formed to a polymer film containing rearearth salt by a spin coating method, a dip coating method or a castingmethod which are public known methods of polymer film, or said obtainedpolymer solution is poured into a poor solution selected from a groupconsisting of fatty acid solvent (decalin, hexane), alicyclic solvent(cyclohexane), CS₂ and a mixture of 2 or more kinds of these solventsand the temperature of said solvent is adjusted to from −20° C. to 60°C. so as to form polymer fine particles whose particle size is from 5 nmto 10000 nm, and obtained dispersion of polymer fine particles is formedto a polymer fine particle film containing rare earth salt by similarmethod to above mentioned polymer film producing method or by anelectrodeposition method.

As the polar solvent, acetone, methylethylketone, tetrahydrofuran,dioxane, acetonitrile, alcohols (methanol, ethanol, isopropanol orothers), N,N-dimethylacetoamide, dimethylformamide orN-methylpyrrolidone (NMP) can be mentioned.

For the production of a photomemory material whose polymer material ispolyimide, it is desirable to prepare a film or fine particles usingpolyamide acid (another name is polyamic acid) which is a precursor ofpolyimide as a starting material, then to imidize the obtained film orfine particles physically or chemically.

E. By irradiating light having wavelength corresponding to thecoordinate bond state of a polymer possessing carbonyl group, rare earthelement ion and oxygen mentioned in item B, for example, light havingwavelength of 254 nm or 304 nm to the produced polymer film containingrare earth salt or polymer fine particle film containing rare earth saltaccording to above mentioned production method have a feature to carryout stable photomemory wherein magnitude of fluorescence level of rareearth ion is intensified depending on irradiation amount of light atroom temperature. Further, by carrying out a heat treatment at thetemperature lower than glass transition point of said rare earth saltcontaining polymer, the magnitude of fluorescence level can be reducedor eliminated to the state due to said heat treatment temperature.

F. Desirably, as a rare earth salt used for the production thephotomemory material, chloride, nitride or cyanide of Eu³⁺ or Tb³⁺ canbe mentioned. Method for production of a material by which multiple bitrecording utilizing said increase of said fluorescence characteristic tothe film whose polymer is polyimide, polyacrylic acid orpolymethylmethacrylic (PMMA) is possible.

In the Invention Relating Aforementioned 2^(nd) Subject,

2-A. In the present invention, as a reprecipitation method which formspolyamide acid fine particles to which functionality providing componentis blended, a method to produce fine particles, in particular, fineparticles of polyimide by a conventional reprecipitation method can beapplied except a point to use a solution prepared by blending a compoundwhich forms a rare earth element ion or a transition metal ion, which issaid functionality providing component or a pigment (as an expression torepresent said blended compounds, an expression of functionalityproviding component can be used) to a polyamide acid solution as asolution to be poured into a poor solution. As shown in FIG. 1, which isa process illustrating view of a reprecipitation method, in A and Bprocesses, solution of polyamide acid 3 containing prescribed amount ofa functionality providing component, e.g. 0.1-10 weight % is poured intopoor solution 1 and polyamide acid fine particles containing prescribedamount of the functionality providing component is obtained byreprecipitation method. Stirring condition of a stirred 2 to stir thepoor solvent when solution 3 is poured in should be accomplish the mostsuited condition according to a scale, however, in a case of beakerscale, 100-3000 rpm is desirable. Further, for the purpose to improvethe dispersability of hybrid fine particles containing preparedfunctionality providing component, 0.1 weight % of a neutral polymersurface active agent (Acrydic: product of DIC Co., Ltd), which ispolyacrylic ester series, can be contained. Then, in C process, aceticacid anhydride/pyridine mixed solvent 5 is added, under constantstirring, wherein stirring condition is depending on a scale and in abeaker scale stirred by 100-3000 rpm, imidized chemically and polyamidefine particles dispersion 6 containing the functionality providingcomponent is obtained. The imidization process can be a thermalimidization or said chemical imidization, for example, after chemicalimidization using acetic acid anhydride/pyridine mixed solvent a thermalimidization can be carried out.

2-B. As a solvent for polyamide acid (can be called as polyamic acid),conventional organic solvent, which is specified as a poor solvent topolyamide acid used for a reprecipitation method and a functionalityproviding subject and has compatibility with a solvent of said polyamideacid, can be used. As the specific example, acetone, chloroform,methylethylketone, tetrahydrofurane, dioxane, acetonitrile, alcohols(methanol, ethanol, isopropanol or others), N,N-dimethylacetoamide,dimethylformamide or N-methylpyrrolidone (NMP) can be mentioned, andN,N-dimethylacetoamide, NMP or dimethylformamide is preferably used.

Solution concentration of polyamide acid is a big factor which effectsto a formed particle size. Especially, when the molecular weight ofpolyamide acid is large, the effect of solution concentration to aparticle size becomes large. The desirable concentration of polyamideacid is 0.1-15.0 weight %, and when the molecular weight is large, 0.5weight % is desirable. Further, when the concentration becomes high, 4.0weight %, in the case of hybrid fine particles possessing fluorescencecharacteristic obtained by blending the rare earth ion forming compound,the tendency of flocculation is observed

2-C. As a solvent which has a compatibility with a solvent of thepolyamide acid and is also a poor solvent to the polyamide acid, hexane(aliphatic solvents), decalin or cyclohexane (alicyclic solvents),benzene or toluene (aromatic solvents), water, alcohols, carbondisulfide or mixture of two or more kinds of these compounds can beused, however, among these compounds, alicyclic solvents and mixedsolvent of alicyclic solvents and carbon disulfide are preferably used.

2-D. Temperature of the poor solvent is sufficient by room temperature,however, by adjusting the temperature condition, the particle size ofthe formed fine particles can be adjusted and is possible to producepolyamide acid hybrid fine particles possessing desired fluorescencecharacteristic can be obtained. However, in a case of temperature lowerthan 30° C., there is a tendency that the particle size of polyamideacid hybrid fine particles becomes larger and polyamide acid hybrid fineparticles having 10000 nm fluorescence characteristic in maximum isformed.

2-E. As tetracarboxylic or dianhydride thereof, which is used to formpolyimide fine particles an to form said polyimide,3,3′-4,4′-benzophenone tetracarboxylic acid (BTDA),3,3′-4,4′-tetracarboxybiphenyl,2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane and dianhydridethereof can be mentioned.

Further, as a diamine which forms polyimide acid being a polyimideprecursor by reacting with said tetracarboxylic or dianhydride thereofand forms polyimide by followed imidizing process,4,4′-diaminodiphenylether, 4,4′-bis(4-aminophenoxy) benzene,1,3′-bis(4-aminophenoxy) benzene, 1,4-diaminobenzene or4,4′-methylenebis(ethylcyclohexylamine) can be mentioned.

The molecule weight of polyimide, basically, voluntarily selectedaccording to a relationship between uses of polyimide hybrid fineparticles obtained by said functionality providing subject, and for thepurpose to produce of desired fine particles stable, it is desirablethat average molecular weight is in the region of 8000-220000.

F. As a functionality providing compound, rare earth elements, desirablylanthanide elements, more desirably a compound of elements whose atomicnumber is 58-70, a compound of transition metal, an organic dye(pigment), quinacridone, titanylphthalocyanine can be mentioned.

EXAMPLE

The present invention will be illustrated in detail according toExamples. And is tending to make the usefulness of the presentinvention, and is not tending to restrict the scope or and claims of thepresent invention.

Example 1

Polyamide acid (average molecular weight: 122955) obtained bypolymerization between 2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride and 4,4-diaminodiphenylether are dissolved inacetone so as the concentration of the polyamide acid to be 0.7 weight%. Eu(NO₃)₃ is added to said solution so as the blending amount of Eu³⁺to said dissolved amount of polyamide acid to be 1 weight %, 5 weight %,10 weight % /polyamide acid, and polyamide acid-Eu(NO₃)₃ acetonesolution is prepared. Then 0.01 ml of said solution is cast on a quartzboard of 20×10 mm, after spin coating or dip coating by 3000 rpm anddried. Thus a polyamide film containing Eu³⁺ is produced. This film ismaintained in the atmosphere of 350° C. for 2 hours so that thermalimidization is completed and polyimide film containing Eu³⁺ is obtained.For the purpose to investigate photomemory characteristic of theobtained polyimide film containing Eu³⁺, light of 6 W and wavelength 254nm is irradiated using a UV lamp, and it is confirmed that magnitude offluorescence level belonging to Eu³⁺ enhances along with the increase ofirradiation time. Results are shown in FIG. 1. Regarding saturatedintensity, polyimide fine particles containing 5 weight % Eu³⁺ indicatesthe highest value, and become 400 times when compared with that ofbefore UV lamp irradiation. By carrying out heat treatment on apolyimide fine particle film containing Eu³⁺ in which magnitude offluorescence level is saturated for 5 minutes, magnitude of fluorescencelevel decreases along with elevation of heat treatment temperature andeliminated completely at 200° C. Results are shown in FIG. 2. Afterfluorescence is eliminated, magnitude of fluorescence level isintensified again by irradiation of UV light. Results are shown in FIG.3.

From this phenomenon, it is understood that the polyimide fine particlefilm containing Eu³⁺ is useful as a re-writable photomemory material.

Example 2

Polyamide acid (average molecular weight: 122955) obtained bypolymerization between 2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride and 4,4-diaminodiphenylether are dissolved in NMP soas the concentration of the polyamide acid to be 0.7 weight %. Tb(NO₃)₃is added to said solution so as the blending amount of Tb³⁺ to saiddissolved amount of polyamide acid to be 5 weight %/polyamide acid, andNMP solution of polyamide acid-Tb(NO₃)₃ is prepared. Then 0.01 ml ofsaid solution is cast on a quartz board of 20×10 mm, after spin coatingor dip coating by 3000 rpm and dried. Thus a polyamide film containingTb³⁺ is produced. This film is maintained in the atmosphere of 350° C.for 2 hours so that thermal imidization is completed, then light of 6 Wand wavelength 254 nm is irradiated on the film using a UV lamp, and itis confirmed that magnitude of fluorescence level belonging to Tb³⁺enhances along with the increase of irradiation time and saturated byapproximately 15 hours. Results are shown in FIG. 4. By carrying outheat treatment on a polyimide fine particle film containing Tb³⁺ inwhich magnitude of fluorescence level is saturated for 5 minutes,magnitude of fluorescence level decreases along with elevation of heattreatment temperature and eliminated completely at 200° C. Afterfluorescence is eliminated, magnitude of fluorescence level isintensified again by irradiation of UV light.

From this phenomenon, it is understood that the polyimide fine particlefilm containing Tb³⁺ is useful as a re-writable photomemory material.

Example 3

Polyamide acid (average molecular weight: 122955) obtained bypolymerization between 2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride and 4,4-diaminodiphenylether are dissolved inacetone so as the concentration of the polyamide acid to be 0.7 weight%. Eu(NO₃)₃ is added to said solution so as the blending amount of Eu³⁺to said dissolved amount of polyamide acid to be 5 weight % /polyamideacid, and polyamide acid-Eu(NO₃)₃ acetone solution is prepared. Then0.01 ml of said solution is cast on a quartz board of 20×10 mm, afterspin coating or dip coating by 3000 rpm and dried. Thus a polyamide filmcontaining Eu³⁺ is produced. This film is maintained in the atmosphereof 350° C. for 2 hours so that thermal imidization is completed andpolyimide film containing Eu³⁺ is obtained. For the purpose toinvestigate photomemory characteristic of the obtained polyimide filmcontaining Eu³⁺, light of 6 W and wavelength 304 nm is irradiated usinga UV lamp, and it is confirmed that magnitude of fluorescence levelbelonging to Eu³⁺ enhances along with the increase of irradiation time,and the magnitude of fluorescence level is saturated by approximately 15hours. By carrying out heat treatment on a polyimide fine particle filmcontaining Eu³⁺ in which magnitude of fluorescence level is saturatedfor 5 minutes, magnitude of fluorescence level decreases along withelevation of heat treatment temperature and eliminated completely at200° C. After fluorescence is eliminated, magnitude of fluorescencelevel is intensified again by irradiation of UV light.

From this phenomenon, it is understood that the polyimide fine particlefilm containing Eu³⁺ is useful as a re-writable photomemory material.

Example 4

Polyamide acid obtained by polymerization between3,3′-4,4′-tetracarboxybiphenyl dianhydride and 1,4-diaminobenzene aredissolved in NMP so as the concentration to be 1 weight %. Eu(NO₃)₃, orTb(NO₃)₃ or Sm(NO₃)₃ or Er(NO₃)₃ is added to said solution so as theblending amount of Eu³⁺ or Tb³⁺ or Sm³⁺ or Er³⁺ to said dissolved amountof polyamide acid to be 5 weight % /polyamide acid, solution ofpolyamide acid-Eu(NO₃)₃ and polyamide acid-Tb(NO₃)₃ and polyamideacid-Sm(NO₃)₃ and polyamide acid-Er(NO₃)₃ are prepared. Then 0.01 ml ofsaid solution is cast on a quartz board of 20×10 mm, after spin coatingor dip coating by 3000 rpm and dried. Thus a polyamide film containingEu³⁺ is produced. For the purpose to investigate photomemorycharacteristic of the obtained polyimide film containing Eu³⁺, light of6 W and wavelength 254 nm is irradiated using a UV lamp, and it isconfirmed that magnitude of fluorescence level belonging to Eu³⁺enhances along with the increase of irradiation time, and the magnitudeof fluorescence level is saturated by approximately 3 hours. Results ofpolyamide acid film containing Eu³⁺ is shown in FIG. 5. By carrying outheat treatment on a polyamide acid fine particle film containing Eu³⁺ inwhich magnitude of fluorescence level is saturated for 5 minutes,magnitude of fluorescence level decreases along with elevation of heattreatment temperature and eliminated completely at 200° C. Afterfluorescence is eliminated, magnitude of fluorescence level isintensified again by irradiation of UV light. In cases of polyamide filmcontaining Tb³⁺ or Sm³⁺ or Er³⁺, same characteristic to the case of Eu³⁺are obtained.

Example 5

Polyacrylic acid (molecular weight: 450000) is dissolved in NMP so asthe concentration to be 1 weight %. Eu(NO₃)₃ is added to said solutionso as the blending amount of Eu³⁺ to said dissolved amount ofpolyacrylic acid to be 5 weight % /polyacrylic acid, and polyacrylicacid-Eu(NO₃)₃ solution is prepared. Then 0.01 ml of said solution iscast on a quartz board of 20×10 mm, after spin coating or dip coating by3000 rpm and dried. Thus a polyacrylic acid film containing Eu³⁺ isproduced. For the purpose to investigate photomemory characteristic ofthe obtained polyacrylic film containing Eu³⁺, light of 6 W andwavelength 254 nm is irradiated using a UV lamp, and it is confirmedthat magnitude of fluorescence level belonging to Eu³⁺ enhances alongwith the increase of irradiation time, and the magnitude of fluorescencelevel is saturated by approximately 24 hours. Results are shown in FIG.6. By carrying out heat treatment on a polyacrylic acid film containingEu³⁺ in which magnitude of fluorescence level is saturated for 5minutes, magnitude of fluorescence level decreases along with elevationof heat treatment temperature and eliminated completely at 140° C. Afterfluorescence is eliminated, magnitude of fluorescence level isintensified again by irradiation of UV light.

Example 6

Poly(methyl methacrylate) (molecular weight: 350000) is dissolved in NMPso as the concentration to be 1 weight %. Solution is prepared so as theblending amount of Eu³⁺ to said dissolved amount of poly(methylmethacrylate) to be 5 weight % /PMMA. Then 0.01 ml of said solution iscast on a quartz board of 20×10 mm, after spin coating or dip coating by3000 rpm and dried. Thus a PMMA film containing Eu³⁺ is prepared. Forthe purpose to investigate photomemory characteristic of the obtainedPMMA film containing Eu³⁺, light of 6 W and wavelength 254 nm isirradiated using a UV lamp, and it is confirmed that magnitude offluorescence level belonging to Eu³⁺ enhances along with the increase ofirradiation time, and the magnitude of fluorescence level is saturatedby approximately 24 hours. Results are shown in FIG. 6. By carrying outheat treatment for 5 minutes on a PMMA film containing Eu³⁺ in whichmagnitude of fluorescence level is saturated, magnitude of fluorescencelevel decreases along with elevation of heat treatment temperature andeliminated completely at 160° C. After fluorescence is eliminated,magnitude of fluorescence level is intensified again by irradiation ofUV light.

Example 7

Polyacrylic acid (molecular weight: 450000) is dissolved in NMP so asthe concentration to be 1 weight %. Eu(NO₃)₃ is added to said solutionso as the blending amount of Eu³⁺ to said dissolved amount ofpolyacrylic acid to be 5 weight % /polyacrylic acid, and polyacrylicacid-Eu(NO₃)₃ solution is prepared. 0.1 ml of said solution is pouredinto 10 ml of cyclohexane (ACRYDIC: 0.1 weight % contained) using amicro syringe at room temperature stirring by 1500 rpm and polyacrylicacid fine particles containing Eu³⁺ is obtained. Observation results bya scanning electron microscope (SEM) are shown in FIG. 7. Film isobtained from said polyacrylic acid fine particles containing Eu³⁺ by acasting method or by an electrodeposition method (fine particlesconcentration in dispersion: 0.1-1 weight %, chargevoltage:10-1000V/cm-⁻¹), and bulk molded product is produced bycontaining 0.2 g of the fine particles in a molding machine of 3 mmdiameter and pressing. Then, for the purpose to investigate photomemorycharacteristic of the obtained polyacrylic acid film containing Eu³⁺,light of 6 W and wavelength 254 nm is irradiated using a UV lamp, and itis confirmed that magnitude of fluorescence level belonging to Eu³⁺enhances along with the increase of irradiation time, and the magnitudeof fluorescence level is saturated by approximately 24 hours. Bycarrying out heat treatment on a polyimide film containing Eu³⁺ in whichmagnitude of fluorescence level is saturated for 5 minutes, magnitude offluorescence level decreases along with elevation of heat treatmenttemperature and eliminated completely at 140° C. After fluorescence iseliminated, magnitude of fluorescence level is intensified again byirradiation of UV light.

Example 8

Polyamide acid (average molecular weight: 122955) obtained bypolymerization between 2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride and 4,4-diaminodiphenylether are dissolved inacetone and polyamide acid-acetone solution of 0.7 weight % is prepared.Eu(NO₃)₃ is added to said solution so as the blending amount of Eu³⁺ tosaid dissolved amount of polyamide acid to be 5 weight % /polyamideacid, and polyamide acid-Eu(NO₃)₃ acetone solution is prepared. Then 0.1ml of said polyamide acid-Eu(NO₃)₃ solution is poured into 10 ml ofcyclohexane (afore mentioned ACRYDIC: 0.1 weight % contained) using amicro syringe at room temperature stirring by 1500 rpm and polyamideacid fine particles containing Eu³⁺ dispersion is obtained.

To the obtained polyamide acid fine particles containing Eu³⁺dispersion, 0.1 ml of mixed solution of pyridine/acetic anhydride whosemolar ratio is 1/1 is added under constant stirring condition andmaintained for 2 hours so as to complete chemical imidization, thenpolyimide fine particles containing Eu³⁺ is obtained. Obtained polyimidefine particles containing Eu³⁺ is observed by a scanning electronmicroscope (SEM). Results are shown in FIG. 9. When UV ray of excitationwavelength 280 nm is irradiated to the obtained polyimide fine particlescontaining Eu³⁺, fluorescence spectrum shown in FIG. 10 is obtained.

Example 9

Polyamide acid (average molecular weight: 122955) obtained bypolymerization between 2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride and 4,4-diaminodiphenylether are dissolved inacetone and polyamide acid-acetone solution of 0.7 weight % is prepared.Tb(NO₃)₃ or Ce(NO₃)₃ is added to said solution so as the blending amountof Tb³⁺ (a) or Ce³⁺ (b) to dissolved amount of polyamide acid in saidpolyamide acid-acetone solution to be 5 weight % /polyamide acid, andsolution of polyamide acid-Tb³⁺ (a) or Ce³⁺ (b) is prepared. 0.1 ml ofsaid solution of polyamide acid-Tb³⁺ (a) or Ce³⁺ (b) is poured into 10ml of cyclohexane (afore mentioned ACRYDIC: 0.1 weight % contained)using a micro syringe at room temperature stirring by 1500 rpm andpolyamide acid fine particles dispersion containing Tb³⁺ or Ce³⁺ isobtained.

To the obtained polyamide acid fine particles dispersion containing Tb³⁺or Ce³⁺, 0.1 ml of mixed solution of pyridine/acetic anhydride whosemolar ratio is 1/1 is added under constant stirring condition andmaintained for 2 hours so as to complete chemical imidization, thenpolyimide fine particles containing Tb³⁺ or Ce³⁺ is obtained. When UVray of excitation wavelength 280 nm is irradiated to the obtainedpolyimide fine particles containing Tb³⁺ or Ce³⁺, fluorescence spectrumshown in FIG. 11 is obtained.

Example 10

Polyamide acid (average molecular weight: 122955) obtained bypolymerization between 2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride and 4,4-diaminodiphenylether are dissolved in NMPand 0.7 weight % polyamide acid-NMP solution is prepared. Eu(NO₃)₃ isadded to said solution so as the blending amount of Eu³⁺ to saiddissolved amount of polyamide acid to be 1 weight % (a), 5 weight % (b),10 weight % (c)/polyamide acid, and polyamide acid-Eu(NO₃)₃ solution isprepared. 0.1 ml of said solutions are poured into 10 ml of cyclohexane(ACRYDIC: 0.1 weight % contained) using a micro syringe at roomtemperature stirring by 1500 rpm and polyamide acid fine particlesdispersions containing Eu³⁺ of said concentration are prepared.

To the obtained polyamide acid fine particles dispersion containingEu³⁺, 0.1 ml of mixed solution of pyridine/acetic anhydride whose molarratio is 1/1 is added under constant stirring condition and maintained 2hours so as to complete chemical imidization, then maintained at 270° C.for 3 hours so as to complete thermal imidization, then polyimide fineparticles containing Eu³⁺ is obtained. The particle size of obtainedpolyimide fine particles is not depending on Eu³⁺ contents and becomesalmost constant. Each polyimide fine particles containing Eu³⁺ areobserved by a scanning electron microscope (SEM). Results are shown inFIG. 12. According to measuring results of fluorescence spectrum atexcitation wavelength 280 nm, magnitude of fluorescence level ofpolyimide fine particles containing 5 weight % of Eu³⁺ is strongest.Fluorescence spectrum at excitation wavelength 280 nm is shown in FIG.13.

Example 11

Polyamide acid (average molecular weight: 122955) obtained bypolymerization between 2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride and 4,4-diaminodiphenylether are dissolved in NMPand 0.7 weight % polyamide acid-NMP solution is prepared. Solutioncharacterized that the blending amount of quinacridone ortitanylphthalocyanine to polyamide acid in said polyamide acid-NMPsolution to be 10 weight % /polyamide acid is prepared. 0.1 ml of theobtained polyamide acid-quinacridone or polyamide acid-perylen ofpolyamide acid-titanylphthalocyanine is poured into 10 ml of cyclohexane(afore mentioned ACRYDIC: 0.1 weight % contained) using a micro syringeat room temperature stirring by 1500 rpm and polyamide acid fineparticles dispersion containing quinacridone or perylene ortitanylphthalocyanine is prepared.

To the obtained polyamide acid fine particles dispersion containingquinacridone or perylene or titanylphthalocyanine, 0.1 ml of mixedsolution of pyridine/acetic anhydride whose molar ratio is 1/1 is addedunder constant stirring condition and maintained for 2 hours so as tocomplete chemical imidization, then maintained at 270° C. for 3 hours soas to complete thermal imidization, and polyimide fine particlescontaining quinacridone or perylene or titanylphthalocyanine isobtained. Obtained polyimide fine particles containing quinacridone isobserved by a scanning electron microscope (SEM). Results are shown inFIG. 14. The polyimide fine particles containing quinacridone indicatesred color, and by the measurement of absorption spectrum, an absorptionis observed in the range from 500 nm to 600 nm.

Example 12

Polyamide acid (average molecular weight: 90000) obtained bypolymerization between 3,3′-4,4′-tetracarboxybiphenyl dianhydride and1,4-diaminobenzene is dissolved in NMP and 0.7 weight % polyamideacid-NMP solution is prepared. Eu(NO₃)₃ is added to said solution so asthe blending amount of Eu³⁺ to said dissolved amount of polyamide acidto be 5 weight % /polyamide acid, and solution is prepared. Then 0.1 mlof said polyamide acid-Eu(NO₃)₃ solution is poured into 10 ml ofcyclohexane (afore mentioned ACRYDIC: 0.1 weight % contained) using amicro syringe at room temperature stirring by 1500 rpm and polyamideacid fine particles containing Eu³⁺ dispersion is prepared.

To the obtained polyamide acid fine particles dispersion containing Eu³⁺, 0.1 ml of mixed solution of pyridine/acetic anhydride whose molarratio is 1/1 is added under constant stirring condition and maintainedfor 2 hours so as to complete chemical imidization, then polyimide fineparticles containing Eu³⁺ is obtained. The obtained polyimide fineparticles containing Eu³⁺ indicates fluorescence by 280 nm excitation.Fluorescence characteristic is not different from that of Example 10.

Example 13

Polyamide acid (average molecular weight: 122955) obtained bypolymerization between 2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride and 4,4-diaminodiphenylether are dissolved in NMPand 0.7 weight % polyamide acid-NMP solution is prepared. EuCl₃ is addedto said solution so as the blending amount of Eu³⁺ to said dissolvedamount of polyamide acid-NMP solution to be 5 weight % /polyamide acid,and solution of polyamide acid-EuCl₃ is prepared. 0.1 ml of saidsolution of polyamide acid-EuCl₃ are poured into 10 ml of 10°C.(a),25°C.(b) and 40°C.(c) of cyclohexane (ACRYDIC: 0.1 weight % contained)using a micro syringe at room temperature stirring by 1500 rpm andpolyamide acid fine particles dispersions containing Eu³⁺ are prepared.

To the obtained polyamide acid fine particles dispersion containingEu³⁺, 0.1 ml of mixed solution of pyridine/acetic anhydride whose molarratio is 1/1 is added under constant stirring condition and maintainedfor 2 hours so as to complete chemical imidization, then polyimide fineparticles containing Eu³⁺ maintaining particle size of 100 nm areobtained. Obtained polyimide particles containing Eu³⁺ are observed by ascanning electron microscope (SEM). Results are shown in FIG. 15. All ofobtained polyimide fine particles containing Eu³⁺ indicate fluorescenceby 280 nm excitation.

Example 14

Polyamide acid (average molecular weight: 122955) obtained bypolymerization between 2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride and 4,4-diaminodiphenylether are dissolved in NMPand 0.7 weight % polyamide acid-NMP solution is prepared. Eu(NO₃)₃ isadded to said solution so as the blending amount of Eu³⁺ to saiddissolved amount of polyamide acid-NMP solution to be 5 weight %/polyamide acid, and solution of polyamide acid-Eu(NO₃)₃ is prepared.0.1 ml of said solution of polyamide acid-EuCI₃ are poured into 10 ml ofcyclohexane (afore mentioned ACRYDIC: 0.1 weight % contained) to whichCS₂ of various volume fractions using a micro syringe at roomtemperature stirring by 1000 rpm and polyamide acid fine particlesdispersions containing Eu³⁺ are prepared. Particle size of formedpolyamide acid fine particles containing Eu³⁺ become small along withthe increase of the blending amount of CS₂.

To the obtained polyamide acid fine particles dispersion containingEu³⁺, 0.1 ml of mixed solution of pyridine/acetic anhydride whose molarratio is 1/1 is added under constant stirring condition and maintained 2hours so as to complete chemical imidization, then maintained at 270° C.for 3 hours so as to complete thermal imidization, and polyimide fineparticles containing Eu³⁺ maintaining particle size of above mentionedpolyamide acid fine particles containing Eu³⁺ are obtained. All ofobtained polyimide fine particles containing Eu³⁺ indicate fluorescenceby 280 nm excitation.

Any changes of fluorescence characteristic of the obtained polyimidefine particles containing Eu³⁺ along with the change of particle sizeare not recognized.

Example 15

Polyamide acid (average molecular weight: 122955) obtained bypolymerization between 2,2-(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride and 4,4-diaminodiphenylether are dissolved in NMPand 0.7 weight % polyamide acid-NMP solution is prepared. Fe(NO₃)₃ (a)or FeCl₃ (b) or CuSO₄ (c) is added to said solution so as the blendingamount of Fe³⁺ or Cu²⁺ to said dissolved amount of polyamide acid-NMPsolution to be 5 weight % /polyamide acid, and solutions are prepared.

To the obtained polyamide acid fine particles dispersion containing Fe³⁺or Cu²⁺, 0.1 ml of mixed solution of pyridine/acetic anhydride whosemolar ratio is 1/1 is added under constant stirring condition andmaintained 2 hours so as to complete chemical imidization, thenmaintained at 270° C. for 3 hours so as to complete thermal imidization,and polyimide fine particles containing Fe³⁺ or Cu²⁺ are obtained.Obtained polyimide particles containing Fe³⁺ or Cu²⁺ are observed by ascanning electron microscope (SEM). Results are shown in FIG. 16. Colorof polyimide fine particles containing Fe³⁺ is light brown and color ofpolyimide fine particles containing Cu²⁺ is light blue. And thesepolyimide fine particles indicates paramagnetism.

INDUSTRIAL APPRICABILITY

As illustrated in the 1^(st) subject of the present invention, a polymermaterial containing rare earth element enhances magnitude offluorescence level corresponding to photo irradiation amount and themagnitude of fluorescence level can be maintained stable on roomtemperature atmosphere, and is possible to be used as a photomemorymaterial. Further, since multiple record by dividing threshold value ofirradiation amount of light is possible, said polymer materialcontaining rare earth element can be used as a photomemory material ofhigh density recording. Furthermore, since said photomemory can berecovered to the initial state by means of heat-treatment, polymermaterial containing rare earth element can be used as a re-writablerecording material. And, by the 2^(nd) subject of the present invention,in a case when a compound which forms rare earth element ion, polyimidefine particles having 5 nm-10000 nm particle size which indicatesfluorescence characteristic can be easily obtained, and in a case when acompound which forms transition metal ion, polyimide fine particleshaving 5 nm-10000 nm particle size indicating magnetism characteristiccan be easily obtained, further, in a case when an organic pigment isblended, polyimide fine particles having 5 nm-10000 nm particle sizewhich is colored or indicates non-linear characteristic can be easilyobtained. Since, these fine particles are a hybrid material withpolyimide, it is possible to provide an useful fine particle materialwith good heat resistance.

1. A photomemory material comprising a polymer with a carbonyl group ina main or a side chain of the polymer and a rare earth ion forming acomplex of rare earth ion-polymer characterized in which magnitude offluorescence level is intensified corresponding with applied photoirradiation intensity and is able to restore to initial state byapplying heat treatment.
 2. The photomemory material of claim 1, whereinthe polymer possessing a carbonyl group is polyimide obtained by areaction of tetracarboxylic acid or dianhydride thereof with diamine. 3.The photomemory material of claim 2, wherein the polymer possessing acarbonyl group is a polymer possessing a carboxylic group or an estergroup thereof in a said side chain.
 4. The photomemory material of claim3, wherein the polymer possessing a carboxylic group or an ester groupthereof in a said side chain is a polymer obtained by an additionpolymerization of ethylene unsaturated group.
 5. The photomemorymaterial according to claim 1, wherein the rare earth element isselected from the group consisting of elements whose atomic number isfrom 58 to
 70. 6. A photomemory material comprising, polymer fineparticles containing a rare earth element ion whose particle size isfrom 5 nm to 10000 nm formed by dissolving a polymer possessing acarbonyl group in a main or a side chain of the polymer and a compoundof a rare earth element which forms a rare earth element in a solventwhich dissolves at least said two components and pouring a polymer filmprepared by containing said rare earth element into the polymer formedfrom the solution and the solution into a poor solution of said twocomponents, or a fine particle film formed from said fine particles orbulky molded product formed from said fine particles.
 7. A method forproduction of polyimide fine particles with particle size in diameterfrom 5 nm to 10000 nm containing a rare earth ion or a transition metalion or a pigment comprising, pouring polyamide acid solution prepared bydissolving a compound which forms a rare earth ion or a transition metalion or a pigment compound in a solution which forms said ions to a poorsolvent to said rare earth ion or transition metal ion or the pigmentcompound and the polyamide acid, forming fine particles of polyamideacid containing the rare earth ion or the transition metal ion or thepigment, then carrying out imidizing treatment on the formed fineparticles of polyamide acid.
 8. The method for production of polyimidefine particles with particle size in diameter from 5 nm to 10000 nmcontaining a rare earth ion or a transition metal ion or a pigment ofclaim 7 comprising, using polyamide acid solution dissolving a compoundwhich forms 0.1-10 weight % of rare earth ion or transition metal ion ora pigment compound.
 9. The method for production of polyimide fineparticles with particle size in diameter from 5 nm to 10000 nmcontaining a rare earth ion or a transition metal ion or a pigment ofclaim 7 wherein a solvent to prepare polyamide acid solution is acetone,acetonitrile, tetrahydrofufuran or chloroform.
 10. The method forproduction of polyimide fine particles with particle size in diameterfrom 5 nm to 10000 nm containing a rare earth ion or a transition metalion or a pigment according to claim 7, wherein the poor solvent isdecalin, cyclohexane, hexane, benzene, toluene, water, alcohols, CS₂ ormixture of two kinds or more.
 11. The method for production of polyimidefine particles with particle size in diameter from 5 nm to 10000 nmcontaining a rare earth ion or a transition metal ion or a pigmentaccording to claim 7, wherein the temperature of the poor solvent isadjusted to from −20° C. to 60° C.
 12. The method for production ofpolyimide fine particles with particle size in diameter from 5 nm to10000 nm containing a rare earth ion or a transition metal ion or apigment according to claim 7, wherein the rare earth element ion is aelement selected from the group consisting of the element whose atomicnumber is from 58 to
 70. 13. The photomemory material according to claim2 wherein the rare earth element is selected from the group consistingof elements whose atomic number is from 58 to
 70. 14. The photomemorymaterial according to claim 3 wherein the rare earth element is selectedfrom the group consisting of elements whose atomic number is from 58 to70.
 15. The photomemory material according to claim 4 wherein the rareearth element is selected from the group consisting of elements whoseatomic number is from 58 to
 70. 16. The method for production ofpolyimide fine particles with particle size in diameter from 5 nm to10000 nm containing a rare earth ion or a transition metal ion or apigment of claim 8, wherein a solvent to prepare polyamide acid solutionis acetone, acetonitrile, tetrahydrofufuran or chloroform.
 17. Themethod for production of polyimide fine particles with particle size indiameter from 5 nm to 10000 nm containing a rare earth ion or atransition metal ion or a pigment according to claim 8, wherein the poorsolvent is decalin, cyclohexane, hexane, benzene, toluene, water,alcohols, CS₂ or mixture of two kinds or more.
 18. The method forproduction of polyimide fine particles with particle size in diameterfrom 5 nm to 10000 nm containing a rare earth ion or a transition metalion or a pigment according to claim 9, wherein the poor solvent isdecalin, cyclohexane, hexane, benzene, toluene, water, alcohols, CS₂ ormixture of two kinds or more.
 19. The method for production of polyimidefine particles with particle size in diameter from 5 nm to 10000 nmcontaining a rare earth ion or a transition metal ion or a pigmentaccording to claim 16, wherein the poor solvent is decalin, cyclohexane,hexane, benzene, toluene, water, alcohols, CS₂ or mixture of two kindsor more.
 20. The method for production of polyimide fine particles withparticle size in diameter from 5 nm to 10000 nm containing a rare earthion or a transition metal ion or a pigment according to claim 8, whereinthe temperature of the poor solvent is adjusted to from −20° C. to 60°C.
 21. The method for production of polyimide fine particles withparticle size in diameter from 5 nm to 10000 nm containing a rare earthion or a transition metal ion or a pigment according to claim 9, whereinthe temperature of the poor solvent is adjusted to from −20° C. to 60°C.
 22. The method for production of polyimide fine particles withparticle size in diameter from 5 nm to 10000 nm containing a rare earthion or a transition metal ion or a pigment according to claim 16,wherein the temperature of the poor solvent is adjusted to from −20° C.to 60° C.
 23. The method for production of polyimide fine particles withparticle size in diameter from 5 nm to 10000 nm containing a rare earthion or a transition metal ion or a pigment according to claim 10,wherein the temperature of the poor solvent is adjusted to from −20° C.to 60° C.
 24. The method for production of polyimide fine particles withparticle size in diameter from 5 nm to 10000 nm containing a rare earthion or a transition metal ion or a pigment according to claim 17,wherein the temperature of the poor solvent is adjusted to from −20° C.to 60° C.
 25. The method for production of polyimide fine particles withparticle size in diameter from 5 nm to 10000 nm containing a rare earthion or a transition metal ion or a pigment according to claim 18,wherein the temperature of the poor solvent is adjusted to from −20° C.to 60° C.
 26. The method for production of polyimide fine particles withparticle size in diameter from 5 nm to 10000 nm containing a rare earthion or a transition metal ion or a pigment according to claim 19,wherein the temperature of the poor solvent is adjusted to from −20° C.to 60° C.
 27. The method for production of polyimide fine particles withparticle size in diameter from 5 nm to 10000 nm containing a rare earthion or a transition metal ion or a pigment according to claim 8, whereinthe rare earth element ion is a element selected from the groupconsisting of the element whose atomic number is from 58 to
 70. 28. Themethod for production of polyimide fine particles with particle size indiameter from 5 nm to 10000 nm containing a rare earth ion or atransition metal ion or a pigment according to claim 9, wherein the rareearth element ion is a element selected from the group consisting of theelement whose atomic number is from 58 to
 70. 29. The method forproduction of polyimide fine particles with particle size in diameterfrom Snm to 10000 nm containing a rare earth ion or a transition metalion or a pigment according to claim 16, wherein the rare earth elemention is a element selected from the group consisting of the element whoseatomic number is from 58 to
 70. 30. The method for production ofpolyimide fine particles with particle size in diameter from 5 nm to10000 nm containing a rare earth ion or a transition metal ion or apigment according to claim 10, wherein the rare earth element ion is aelement selected from the group consisting of the element whose atomicnumber is from 58 to
 70. 31. The method for production of polyimide fineparticles with particle size in diameter from 5 nm to 10000 nmcontaining a rare earth ion or a transition metal ion or a pigmentaccording to claim 17, wherein the rare earth element ion is a elementselected from the group consisting of the element whose atomic number isfrom 58 to
 70. 32. The method for production of polyimide fine particleswith particle size in diameter from 5 nm to 10000 nm containing a rareearth ion or a transition metal ion or a pigment according to claim 18,wherein the rare earth element ion is a element selected from the groupconsisting of the element whose atomic number is from 58 to
 70. 33. Themethod for production of polyimide fine particles with particle size indiameter from 5 nm to 10000 nm containing a rare earth ion or atransition metal ion or a pigment according to claim 19, wherein therare earth element ion is a element selected from the group consistingof the element whose atomic number is from 58 to
 70. 34. The method forproduction of polyimide fine particles with particle size in diameterfrom 5 nm to 10000 nm containing a rare earth ion or a transition metalion or a pigment according to claim 11, wherein the rare earth elemention is a element selected from the group consisting of the element whoseatomic number is from 58 to
 70. 35. The method for production ofpolyimide fine particles with particle size in diameter from 5 nm to10000 nm containing a rare earth ion or a transition metal ion or apigment according to claim 20, wherein the rare earth element ion is aelement selected from the group consisting of the element whose atomicnumber is from 58 to
 70. 36. The method for production of polyimide fineparticles with particle size in diameter from 5 nm to 10000 nmcontaining a rare earth ion or a transition metal ion or a pigmentaccording to claim 21, wherein the rare earth element ion is a elementselected from the group consisting of the element whose atomic number isfrom 58 to
 70. 37. The method for production of polyimide fine particleswith particle size in diameter from 5 nm to 10000 nm containing a rareearth ion or a transition metal ion or a pigment according to claim 22,wherein the rare earth element ion is a element selected from the groupconsisting of the element whose atomic number is from 58 to
 70. 38. Themethod for production of polyimide fine particles with particle size indiameter from 5 nm to 10000 nm containing a rare earth ion or atransition metal ion or a pigment according to claim 23, wherein therare earth element ion is a element selected from the group consistingof the element whose atomic number is from 58 to
 70. 39. The method forproduction of polyimide fine particles with particle size in diameterfrom 5 nm to 10000 nm containing a rare earth ion or a transition metalion or a pigment according to claim 24, wherein the rare earth elemention is a element selected from the group consisting of the element whoseatomic number is from 58 to
 70. 40. The method for production ofpolyimide fine particles with particle size in diameter from 5 nm to10000 nm containing a rare earth ion or a transition metal ion or apigment according to claim 25, wherein the rare earth element ion is aelement selected from the group consisting of the element whose atomicnumber is from 58 to
 70. 41. The method for production of polyimide fineparticles with particle size in diameter from 5 nm to 10000 nmcontaining a rare earth ion or a transition metal ion or a pigmentaccording to claim 26, wherein the rare earth element ion is a elementselected from the group consisting of the element whose atomic number isfrom 58 to 70.